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Leigh-Ann Mulcahy QC

Call: 1993 QC: 2009

Leigh-Ann Mulcahy QC is listed by the legal directories as a leading silk in four fields (Professional Negligence, Product Liability, Insurance and Administrative & Public Law).

She has been described in the legal directories as follows: “an incredibly good appellate advocate”; “at the top of her field”; "truly brilliant"; "she is an iron fist in a velvet glove"; "first-rate"; “outstanding”; “formidably intelligent”; “extremely bright and highly organised”; “prodigiously hard-working and possesses both a first-class brain and very sound judgment”; “excellent, thorough...with encyclopaedic knowledge of the case-law”; “tenacious with the opposition”; “stunning performances" in court. She is also considered to be “very user-friendly”, “one of the most approachable QCs, and very knowledgeable” who “has strong attention to detail and picks up complex matters quickly”  she is also praised for her "ease of manner with both peers and clients".

Leigh-Ann has wide advocacy experience at all levels, including the Supreme Court and House of Lords. She succeeded in two cases before the Supreme Court (The Atomic Veterans Litigation and The Employers' Liability Policy Trigger Litigation) and one before the House of Lords (Medcalf v Mardell). She is currently appearing in another appeal to the Supreme Court in International Energy Group Ltd v Zurich which relates to the insurance of asbestos liabilities. She also acts as an advocate and arbitrator in commercial and insurance arbitrations and is currently acting in a very high value international arbitration. Leigh-Ann has extensive experience of handling group/multi-party litigation and is especially noted for cases involving complex technical or scientific evidence.

Leigh-Ann was appointed First Counsel to the Welsh Government in November 2013, a role which she combines with her other practice. Prior to her appointment to silk, Leigh-Ann held the appointment of Treasury Counsel (A Panel) and since taking silk she has continued to act in cases for the UK Government upon the nomination of the Attorney-General. Over the course of some 18 years, she has acted for a wide range of Government departments and other public bodies on issues including public law, EC law and human rights.

Leigh-Ann accepts instructions as a mediator (CEDR accredited) and has been appointed as a Senior Decision-Maker for the Guernsey Financial Services Commission.

She specialises in the following areas of practice:

  • Professional liability, particularly claims involving lawyers and accountants, insurance brokers and financial services professionals;
  • Product liability, including commercial products and claims in relation to pharmaceuticals, food safety, medical devices and blood products;
  • Insurance and reinsurance, particularly liability insurance;
  • Public law and human rights;
  • Commercial litigation, including financial services, commercial fraud and utilities law;
  • Mediation;
  • Arbitration.

Major cases include:

  • International Energy Group Ltd v Zurich [2013] PIQR P10, an employers’ liability insurance case concerning asbestos/mesothelioma risks and in particular whether an insurer has any right of recoupment from a solvent employer in respect of uninsured periods, which is currently on appeal to the Supreme Court;
  • The Employers’ Liability Insurance Trigger Litigation (Durham v BAI (Run Off) Ltd [2012] 1 WLR 867), a multi-party action and major liability insurance case concerning asbestos/mesothelioma risks, which was appealed to the Supreme Court. She represented Zurich Insurance Company.
  • The Atomic Veterans Litigation (AB & ors v Ministry of Defence [2013] 1 AC 78), a large multi-party action arising out of the British nuclear tests in Australia and the South Pacific in the 1950s which was again appealed to the Supreme Court. She represented the Ministry of Defence.
  • The Miners' Knee Litigation (Davies v Secretary of State for Energy and Climate Change [2012] EWCA Civ 1380), a large group action arising out of the development of osteoarthritis in the knee from coal mining. She represented the Department for Energy and Climate Change in an appeal by the claimants to the Court of Appeal.
  • The Porton Down Litigation, a multi-party action arising out of a programme of non-therapeutic experimentation at Porton Down with chemical warfare agents and antidotes. She represented the Ministry of Defence.
  • Medcalf v Mardell [2003] 1 AC 120, a professional liability claim involving the first and only wasted costs case to be heard by the House of Lords. Leigh-Ann appeared on behalf of the successful barrister respondents. As junior counsel, she presented part of the appeal orally before the House of Lords.
  • The BSE Litigation, a multi-party action which arose out of the development of BSE/vCJD and resulted in an ex gratia compensation scheme being set up by the Government. Leigh-Ann acted for the Department of Health and Department of Environment, Food and Rural Affairs. During 2010, she defended a major judicial review of the vCJD Compensation Scheme on behalf of the Department of Health ((2010) Med LR 204 & [2010] EWHC 1225).
  • Aspirin/Reyes Syndrome [2002] Lloyd’s Rep Med 333, a product liability claim in which Leigh-Ann acted on behalf of the Committee on the Safety of Medicines.
  • The Creutzfeldt-Jakob Disease/Human Growth Hormone Litigation, a multi-party product liability action by claimants who had developed CJD as a result of taking human growth hormone or had received the medicine but were “worried well” ((2000) 54 BMLR 1, 79, 85, 95, 100, 103, 104, 111; [2000] Lloyd’s Rep Med 161). Leigh-Ann acted for the Department of Health and Medical Research Council.

She is Consultant Editor and contributor to The Law and Regulation of Medicines (OUP), Editor of Jackson & Powell on Professional Liability (7th ed) (Thomson Reuters), contributor to R. Goldberg’s Perspectives on Causation (Hart) and General Editor of Human Rights and Civil Practice (OUP).

Leigh-Ann is a non-executive director of Bar Mutual Indemnity Fund Ltd. She is called to the Bar of the Republic of Ireland. She is also an international advanced advocacy trainer.


M.A. (Cantab.) LL.M. (Osgoode, Canada) Dip. E.C.Law (Kings). Scholarships/prizes: Foundation Scholarship (Jesus College); Squire Scholarship (Cambridge University); C.J. Hamson Prize for Contract Law (Cambridge University); Major Scholarship (Inner Temple); Commonwealth Scholarship.